Breech block controlling mechanism for a retarded blow back gun



E. H. BRADLEY Oct. 9, 1955 BREECH BLOCK CONTROLLING MECHANISM FOR ARETARDED BLOW BACK GUN 2 Sheets-Sheet l Filed Dec. 27. l952 .F5 Mm 71 TY n H @A E. H. BRADLEY Oct. 9, 1956 BREECH BLOCK CONTROLLING MECHANISMFOR A RETARDED BLOW BACK GUN 2 Sheets-Sheet 2 Filed Dec. '27, 1952INVENTOR. Ear/ HfaQ//a'y ATToRNaS/s.

2,765,710 BREECH BLOCK coN'rROLLmG MECHANISM FOR A RETARDED BLOW BACKGUN Earl H. Bradley, Seeknk, Mass. Application December 27, 1952, SerialNo. 328,244 12 Claims. (Cl. 89-195) This application refers to a gun andmore particularly to the control for a breech bloc-k for asemi-automatic piston or the like.

Experts find a iixed 'barrel type of .construction as used in thesemi-automatic pistons of a smaller calibre, such for instance as .22Icalibre having a solidly fixed barrel, more accurate than a largercalibre piston where fthe barrel slides relative to the fname.

yIn arms of larger calibre having cartridges powerful enough to be ofmilitary value it is not practical to provide a slide heavy enough sothat the gun can safely operate as a straight blow black weapon.Military pistols have therefore been made with locked breeches so thatduring the period -when the bullet is moving through the barrel, lthebarrel and breech recoil together. This motion is usually used to unlockthe breech, permitting the slide to continue its motion, removing theempty cartridge case.

lThis construction necessarily means that the barrel cannot be iixed in'theV frame land that the accuracy of the arm is substantiallyrrlessthan could be realized with -a fixed barrel.

One of the objects of this invention is to provide in the larger calibresemi-automatic pistols or other guns a -Xed barrel Iand still preventdetrimental motion of the slide during the initial period when gaspressures in the barrel are dangerously high.

More specifically an object `of this invention is to multiply theinertia of a small Weight by requiring that its movement occur through amechanical disadvantage. Yet more specifically this mechanicaldisadvantage is provided by causing the small weight to move through asubstantial distance.

Another 4object of the invention is to retard the movement of the breechblock by adding to its eiective inertia without increasing its weight orby utilizing a small additional Weight in addition to the weight of thebreech block itself.

Another object of the invention is to provide greater reliance uponinertia, which is constant, than upon friction, where the two areinvolved, the friction being more variable and thus to provide amoreuniform operation ofthe breech block.

With these and other objects in view, the invention consists of certainnovel features of construction as will be more fully described .andparticularly pointed out in the .appended claims.

ln the `accompanying drawings:

Figure 1 is a sectional view showing the breech block in tiringposition;

Figure 2 is a fragmental view of the part shown in Figure 1 but showingthe breech block in open position;

`Figure 3 is a perspective view of the lrst or the link pivoted to theframe of the gun;

Figure 4 is a sectional view 'on line 4 4 of Figure 3;

Figure 5 is Ia sectional view on line '5-5 of Figure 1 I'through thepivotal connection of this to the trame;

Figure 6 is a section on line 6 6 of Figure 4;

arent Figure 7 is a perspective =view of the other or second link whichis pivoted to the breech block;

Figure 8 is Ia side elevational view of a modied construction;

Figure 9 is a similar view but showing the breech block just prior toits .release from the retarding mechanism;

yFigure l0 is a section view taken substantially along line fill-10 ofFigure 8; and

Figure 111 is a perspective view of the breech block retardingmechanism.

In proceeding with this invention instead of using a toggle linkconnection between the frame and the breech block in which the pivotsmust be near a straight line in .order to provide the resistancenecessary .and in which friction plays a large part, l have provided `aflink-age in which lthe pivots may be further from a straight line inthe initial ring position with a greater proportion `of the resistanceprovided by inertia, which is constant and therefore provides -a morereliable operation, and in order to accomplish this, one means is topivot one link 'on the frame at one end and pivot -another on the breechblock at one of its ends, while providing a sliding connection by meansof a slot and pin-like arrangement between the two links so that theresistance may be great due to the inertia andy large movement required-at the tiring position ,when the forces are greatest, but one in whichas the forces reduce, the mechanical advantage due to the swinging ofIthe links will increase so that when the forces yare weak, the movementof the slide may be the greatest in arriving at its full open position.

With reference to vthe drawings 10 designa-tes .generally the frame of apistol of Ithe retarded blow back semiautomatic type in which the barrel1.1 is [fixed tothe Itrame such as being threadedas at 12 into apor-tion of the frame ai: -i-ts inner end. A handle is provided at 13which receives a clip y114 of cartridges comprising bullets 15 andshells 16. A breech block y1:7 is slidable with reference to the frame10 and is controlled by means lwhich will Iadd to its inertia at theinitial or :firing position but which towards the end of its movementwill decrease its resist- `ance and permit it to move to wide openposition, as shown in Figure 2.

This mechanism in one form comprises a tirst link 20, as shown inperspective in Figure 3, which is pivoted to the frame by means of lapin 21 extending through the opening 22 `at one end of the link. TheIend 23 of this link is partially received in the breech block which isrecessed as at 24 to receive .this and the other link which controls the"breech block. By observation of Figures 3 and 4, the end 23 of link 20will be seen to be thicker than the major portion of the link, thusincreasing the weight of the link at this `end 23. This iirst link `20is recessed `as at 2'5, and one of its walls is slotted las at 26.

The second link 27, l'as shown in Figure 7 in perspective, is .pivotedlas -at 28 in a recess in the breech lblock '17 by the pin 28 extendingthrough the opening 29 in one end of the link 27. This link l27 ts intothe recess 2'5 in the link -20 and is `stepped -as at 30 -so that itstrunnion pin or `other circular projection 31 will extend into the slot26 and be pivoted yas well as slidable in this slot. This ling 27, whichis the second link, nests within .the iirst link 20, as--shown in Figurel, when the parts are in tiring position. Link '27 has a semi-circularend 72 which in vthe closed position engages a semi-circular .groove73Yin link 20 which is located between the mid point of link 20 and itspivot 21. When in this nested position, the axis of the pivot 31 isoutwardly of la line between the axes of the pivots 21 and 28 so thatthe angle between line connecting pivots 21 .and 28 and the line 7:1connecting pivots 31 and 28 is less than 30 so that when pressure isapplied on Ithe. airis 28 toward the axis 211, there will be .a tendencyof the link 20 to swing about :gremio Y 3 its pivot -21 clockwise to theposition, as shown ln Figure 2. A spring 33 is anchored as at 34 in thehandle and is :attached as at 3'5 on the bearing 36 at one side of theaxis of the pivot 21 so as to tend to swing the link 20 downwardly intofiring position.

Assuming the :cartridge shown in Figure l is tired, the pressure of thegasses in the chamber tending to drive the bullet out of the barrelexerts a force upon the breech block 17 tending to move the breech blockrearwardly. The pressure received by the breech block 17 will be appliedthrough pivot pin 28 toward pivot pin 21 through the link 2.7 whichapplies pressure at bearing 72 along line '71 slightly outwardly fromthe center of the pivot 21. Thus there will be a tendency for link 20 toswing clockwise as shown in Figure l about the pivot 21. As these threepivots 28, 72, and 21 are nearly in line, there is a mechanicaldisadvantage so as to add resistance to the inertia of the breech block17 against sliding rearwardly under the pressure of the gases. Thus thisinertia causes the breech block to move very slowly from its firingposition and sufficient so that there will be a retarding for a lengthof time to permit the bullet 15 to be discharged from the barrel. As thelirst link 2,0 swings about pivot 21, its surface 74 acts upon link 27to shift the point at which it bears upon link .20 away from pivot 21.After the link 20 lifts at its end 23 to a point at which the anglebetween the link 27 and the wall of the slot 26 is greater than a rightangle, the pivot 31 slides rapidly in the slot 26 and more rapidlyincreases the leverage at its point of application to the lever 20 byincreasing its distance from the pivot 21, thus increasing themechanical advantage which the reducing gas pressure applies to the link20 which force tends to swing it about the pivot 21 until near the endof its stroke where the link 27 is applying its force at the end 37 ofthe slot 26, as shown in Figure 2, so as to give a maximum leverage onthe link 20 in swinging it through its motion about the pivot 21. Thespring 33 is increasing its resistance, however, to the motion of thelinks, it being shown as applying its maximum force in the open positionin Figure 2. As soon as the breech block is withdrawn, as shown inFigure 2, another bullet from the clip will be advanced into position sothat when the breech block again closes, the bullet will be in thebarrel ready to again lire. By this arrangement I am able to maintainthe barrel fixed and the breech block without substantial motion untilthe bullet has left the barrel. Thus the accuracy of the gun ismaterially increased.

If it is desired to open the breech block by hand, it is merelynecessary to place the thumb and finger on opposite sides of the knurledportions 40. 40 of the rst link 20 and swing this by hand about thepivot 21.

As the other parts of this gun are standard equipment, it is thoughtunnecessary to describe the same in detail.

In Figures 8-ll, inclusive, there is shown a modification in which alever 50 (see Figure ll) is arranged so as to provide for the delayedaction in the opening of the breech block of the gun just subsequent tothe firing thereof. This lever 50 comprises parallel arms 51 and 52joined at one end thereof by an integral bridge 53 which is arcuate insubstantially the curvature of the gun barrel or semi-circular as seenin Figures l and 11. These arms 51, 52 are each provided with alignedmounting openings 54 and each has a recess S5 extending inwardly fromthe upper edge thereof and in line with each other. One wall of eachrecess is of the form of a cam surface 56. The arm S1 is extendedrearwardly beyond the recess 55 as at 57, the upper edge of which tapersdownwardly as at 57 so as to provide a rest arm as will presentlyappear.

The lever l) is pivotally mounted on the gun body at a location adjacentthe inner edge of the breech block 58 as by means of pivot pins ortrunnions 59 which may be suitably secured on either side of the gunbody to project therefrom through the said openings 54 and with theirends upset in a manner of a rivet. The arms 51, `52 are sufcientlyspaced from the gun body to permit free rocking motion thereof, and atorsion type spring 60 encircles each pivot pin 59 and is arranged toexert a yieldable force on said lever S0 to swing it in acounterclockwise direction as seen in Figures 8 and 9 to resilientlyhold the bridge portion 53 in engagement with the gun barrel (see Figure10). Pins 61 project from the breech block 58 to be received in saidrecess 55 to engage the cam surfaces 56 thereof. In the instantdisclosure the pins 59, 61 are positioned to be in a plane extendingaxially of the gun barrel.

Referring to Figure 8, it will be apparent that upon a rearward movementof the breech block 58, the pin 61 will exert a force on the cam surface56 in a direction tending to rock the lever 50 about its fulcrum 59. Thesurfaces of the cams 56 are made a little greater than a right angle toa plane passing centrally through pins 59, 61, and said force will acton said cam surfaces in a direction tending to move said lever 50 in aclockwise direction. When the gun fires, pressure of the shell on thebreech block 58 will be transmitted through pins61 on to cam surfacw 56and rock lever 50 about its fulcrum 59. lt is apparent that the motionof the lever at the bridge 53 is much greater than the rearward motionof the breech block 58 so that the inertia aect of the lever S0 isconsiderably greater than the corresponding weight in the breech blockand causes a hesitation in the rearward movement of the said breechblock 58. Thus, I am able to control the hesitation or retard theopening of the breech block 58 by a choice of length of lever armforwardly of the fulcrum 59 or by increasing or der creasing thedistance between the said fulcrum 59 and the cam surface 56. Also, asthe angle of the surface 56 is increased, the turning componentincreases and the retarding effect of the inertia of the lever 50decreases. A substantial part of the inertia of lever 50 is due to theweight of the bridge 53. In order to obtain sucient multiplication ofthe inertia of the weight at the ends of arms S1, 52, the center ofgravity of the lever arm on one side of the pivot should be a distancemuch greater from the pivots 59 than are the cam surfaces 56.

I have described the angle of the cam surfaces S6 as being made greaterthan a right angle, and in practice it will be found than an angle up todegrees will be required depending upon the material of the lever S0 forthe turning components of the force exerted upon the cam surfaces 56 tobe sucient to overcome the elect of the friction between the pin 61 andthe surfaces 56 caused by the pressure of said pins 61 on said surfaces56. I have shown the surfaces 56 as being linear. However, thesesurfaces may be varied to give a large initial delay and then anincreasing angle above this delayed action to provide lesser delay at asubsequent period in the opening movement of the breech block 58.

Upon the lever 50 being rocked to position its cam surfaces 56 free ofthe pin 61, the breech block 52 will be free to continue its action inthev usual manner. Upon the passing of the pin 61, which is adjacent tothe arm 51, beyond the end of the reset arm 57, the lever 50 under urgeof the spring 60 will be rocked in a counterclockwise direction towardthe initial position, and the tapered edge 57 will be at a position tobe engaged by said pin 61 upon the return or forward motion of thebreech block 58. The said pin 61 upon riding over the edge 57 will causesaid lever 50 to be moved clockwise a distance suicient for the pin 61to pass thereby and position each pin in its recess upon said leverrocking to initial position under urge of said spring 60.

The action of said breech block 58 and lever 50 is very sudden, and inorder to prevent injury to the hand of the user by the reset arm 57, aguard 62 is provided. This guard 62 may be conveniently made of sheetmaterial cut to a form as shown (see Figures 8 and 9) to be positionedto cover the path of movement of said arm 57. The shield may be securedin place in any convenient manner as by means of screw fastenings 63.

I claim:

1. In a retarded blow back gun, a frame, a barrel fixed thereto, abreech block slidable relative to the frame, a first link pivoted to theframe, a second link pivoted to the breech block and means to connectsaid links together at a location between the pivot of the first link tothe frame and the mid point thereof when in closed position by a slidingrelationship movable along the rst link away from its pivot to applypressure above the pivot of the first link to the frarne to lift thelink upwardly against the force of gravity.

2. In a retarded blow back gun, a frame, a barrel fixed thereto, abreech block slidable relative to the frame, a first link pivoted to theframe and provided with a slot extending lengthwise thereof and a secondlink pivoted at one end to the breech block with the other end pivotallyand slidably located in said slot at a location between the pivot of thefirst link to the frame and the mid point thereof when in closedposition.

3. In a retarded blow back gun as in claim 1 wherein a spring acts uponthe link pivoted to said frame urging the parts toward firing position.

4. In a retarded blow back gun as in claim 2 wherein a spring acts uponthe link pivoted to said frame urging the parts toward firing position.

5. In a retarded blow back gun, a frame, a barrel fixed thereto, abreech block slidable relative to the frame, a lever pivoted to theframe and carrying a weight on one side of the pivot and a cam surfaceon the other, the distance of the center of gravity of the weight fromthe pivot being much greater than the distance of said cam surface fromthe pivot, means carried by the breech block engaging said cam surfaceto swing the lever about its pivot upon rearward movement of the breechblock, the shape of said cam surface being such that the contact of theengaging means therewith increases its distance from the pivot as thelever swings about the pivot.

6. In a retarded blow back gun, a frame, a barrel fixed to the frame, abreech block slidable relative to the frame, and means retardingmovement of the block comprising a fulcrnmed lever rand a member forapplying the reactive force of the bullet to said lever at an angleslightly outwardly from the line connecting the centers of the pivots ofsaid member and lever, said member sliding along said lever to apply itsforce at a greater distance from the fulcrurn as the breech block moves,and at an intermediate position of movement of the block suddenlyshifting its action to thereafter change its resistance to the movementci' the block to open position.

7. In a retarded blow back gun, a frame, a barrel fixed thereto, abreech block slidable relative to the frame, a first link having a fixedpivot and a groove with a semi-circular cross section at a point betweenits mid point and its pivot, a second link having an end with asemi-circular cross section which in closed position bears in saidgroove of the first link with the line connecting the center of saidsemi-circular end with the pivot of the second link making an angle ofless than 30 with the line connecting the centers of the pivots of thetwo links.

8. in a retarded blow back gun as in claim 7 wherein the first link ispivoted to the frame and the second link is pivoted to the breech block.

9. In a retarded blow back gun, a frame, a barrel fixed thereto, abreech block slidable relative to the frame, a first link pivoted to theframe having a groove with a semi-circular cross section at a pointbetween its mid point and its pivot and having its end farthest from thepivot Weighted, a second link pivoted to the breech block and having anend semi-circular in cross section which in closed position bears insaid groove in the first link with the line connecting the center ofsaid semicircular end with the pivot of the second link making an angleof less than 30 with the line of centers of the first and second linkswhen the linkage is closed with the Weighted end of the first link closeto the pivot of the seco-nd link.

10. In a retarded blow back gun as in claim 9 wherein the first link hasa slot running lengthwise and said second link provided with cylindricalprojection at its semicircular end engaging the slot so that neitherVlink may move Without moving the other.

11. In a retarded blow back gun as in claim l() wherein the point ofbearing of the second link upon the first link is continually shifteduntil it reaches the end of its slot during the rearward movement of thebreech block to increase its distance from the pivot of the first link.

12. in a retarded blow back gun as in claim 1l wherein a spring actsupon the link pivoted to said frame urging the parts towards firingposition.

References Cited in the file of this patent UNITED STATES PATENTS804,506 Schwarzlose Nov. 14, 1905 821,922 Burgess May 29, 1906 1,073,452White Sept. 16, 1913 1,147,780 Borchardt July 27, 1915 1,985,493 Gebaueret al Dec. 24, 1934 FOREIGN PATENTS 229,760 Germany Jan. 7, 1911

